####018004531#### FXUS63 KABR 162031 AFDABR Area Forecast Discussion National Weather Service Aberdeen SD 331 PM CDT Fri May 16 2025 .KEY MESSAGES... - Winds will begin to subside this evening/overnight, as will the rainfall. Less than one-quarter inch additional rainfall forecast tonight (7PM CDT and beyond) for most locations. - The probability of low temperatures falling to 36F degrees or colder (frost potential) Saturday night is greater than 90 percent across northeast South Dakota and west central Minnesota. - Another round of showers and thunderstorms will impact the area Sunday through Tuesday. The probability of seeing 1 inch or greater of rain over a 48-hour period, ending at 7 am Tuesday, is 60 percent or greater for a large portion of the forecast area (James River westward to central SD). Severe storm threat is very low. && .DISCUSSION... Issued at 255 PM CDT Fri May 16 2025 Fairly persistent band of light to moderate rain has been affecting central SD for a good chunk of the day, whereas locations further east have seen more breaks in the precipitation. As we head into the evening/overnight hours, the surface low responsible for the rainfall will begin tracking eastward towards the northern Great Lakes, thus bringing an end to the shower activity. As for winds, still seeing a large portion of the CWA gusting over 45 mph, although mainly west of the James River. These winds will begin to subside after 00Z this evening and will go ahead and leave the wind headlines in place without changes for the time being, which has everything expiring at 00Z. Focus then shifts to frost potential tonight/tomorrow night. Don't see high frost potential tonight as we'll keep cloudy skies and breezy conditions in place much of the night, which should prevent temps from dropping too drastically. That said, forecast lows to get to around 34-36 degrees over north central SD, where will should be "lightest" come morning, and where there is better potential for clearing to take place by sunrise. Across the eastern CWA, blended in about 50 percent NBM90 lows just to favor warmer end guidance with all the cloud cover forecast to hang on. Better frost potential arrives Saturday night into Sunday morning, although perfect radiational cooling conditions don't really line up the greatest. Also, it appears clouds will be on the increase from the southwest between 06-12Z Sunday. That said, the locations where winds appear lightest and skies stay clear the longest would be the eastern CWA, where probability in the NBM for lows 36F or colder are greater than 90 percent. Will let mid shift go ahead and issue any potential headlines from this as there is still some uncertainty in the radiational cooling setup. Rain chances return to the forecast Sunday through Tuesday as another area of low pressure approaches the region. Surface low track looks to be south of the CWA, generally across NE/KS, but good agreement amongst the models in showing precip overrunning into SD Sunday night into Tuesday. Potential to pick up an inch or more rainfall is rather high, as 48-hour probabilities ending at 7am Tuesday in greater than 60 percent for much of central SD into the James River valley. Potential for severe storms looks rather low at this time due to an overall lack of unstable air. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1237 PM CDT Fri May 16 2025 Terminals KABR,KATY,KPIR,KMBG Generally MVFR CIGs will continue to affect the region through the TAF period. There may be some patches of IFR clouds as well late tonight into early Saturday morning. Also, clouds are forecast to be on the decrease from west to east across the region on Saturday, and have reflected this in a TEMPO group for SCT conditions towards the end of the TAF period across KPIR/KMBG. Areas of -SHRA/SHRA/-RA and BR will continue to affect the area today, with precipitation eventually coming to an end this evening. Periodic MVFR (potentially IFR?) VSBY is possible with precipitation. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...High Wind Warning until 7 PM CDT /6 PM MDT/ this evening for SDZ003-015-033-045. Wind Advisory until 7 PM CDT this evening for SDZ004>011-016>023- 034>037-048-051. MN...None. && $$ DISCUSSION...TMT AVIATION...TMT ####018004301#### FXUS65 KBOI 162031 AFDBOI Area Forecast Discussion National Weather Service Boise ID 231 PM MDT Fri May 16 2025 .SHORT TERM...Tonight through Sunday night...Mostly cloudy skies this afternoon with light showers over the mountains as the system that impacted the area continues to move east. The next system arrives on Saturday morning in central OR with showers and thunderstorms developing. As this system moves east, showers become widespread with isolated thunderstorms across southwest ID and southeast OR. The strongest thunderstorms will be south of the Snake Basin on Saturday afternoon, with some storms producing hail up to 0.5". Some storms may produce gusts up to 50 mph as well, but the highest threat of wind gusts will be south of the Snake Basin in Owyhee and southern Twin Falls County. The system will generally produce 0.25 to 0.50 inch in the lower elevations, and 0.50 to 1.00 inch over the mountains into Sunday. Wrap around precipitation continues over the mountains on Sunday, as snow levels lower to 4000-5000' MSL Sunday afternoon. Snow amounts of 3 to 6 inches possible over the mountains above 7000 feet with this storm. Temperatures will be quite cool as the center of the system moves overhead, with values around 15 degrees below normal. Windy conditions expected on Sunday with northwest winds 20-30 mph with gusts to 45 mph across the Treasure and Magic Valleys. A wind advisory may be needed across the I-84 corridor but will hold off on issuing this shift. Drier conditions expected by Sunday night with the start of a warming trend thereafter. .LONG TERM...Monday through Friday...Quiet weather through the next week. As the system that brought us our weekend weather moves out of our area, low amplitude ridging will begin to set in aloft. This will allow for temperatures on Monday to warm nearly 10 degrees above what they were Sunday...but still leaning below normal. The upper level ridge begins to flatten through tuesday, putting our area under near zonal flow through Friday. While most of our area will remain dry, shortwaves embedded in the flow aloft will bring periodic chances of precipitation over the West-Central Mountains. The best chance of precipitation will be Tuesday afternoon with a 40% chance in far northern Valley county. Winds will remain breezy through early next week as a surface low continues to exit our area, with gusts up to 30 MPH on Monday in the western Magic Valley. Temperatures will warm to near normal by Tuesday, and then hover there with little fluctuation in the daytime highs/overnight lows. Snow levels follow a similar trend rising from 6-7 kft on Monday to 8-9 kft by Friday. && .AVIATION...Mainly VFR. Low ceilings and MVFR conditions near KMYL, ceilings will rise through the afternoon. Mtns obscured. Rain showers and thunderstorms will enter eastern Oregon early Saturday morning and move into SW Idaho before 18z. MVFR possible in showers/thunder. Snow Levels: 7-8 kft MSL. Surface Winds: W-NW 5-15 kt becoming variable under 10 kt overnight. Gusty erratic winds up to 40kt near storms. Winds aloft at 10kft MSL: W-NW 10-25 kt becoming variable 20-30 kt Saturday morning. KBOI...VFR. Rain showers Saturday morning lasting through Saturday afternoon. Thunderstorms possible (20-30%) from 17/15z to 18/03z, MVFR and gusts to 30 kt possible in thunder. Surface winds: W-NW 8- 12 kt becoming E-SE 6-8 overnight. Weekend Outlook...VFR to MVFR and a slight chance of IFR Saturday with widespread precipitation and isolated thunderstorms. Mountains obscured at times. Snow levels 7000-8500 ft MSL Saturday. Precipitation moves out from west to east Sunday, with improving conditions (mostly VFR, but mountain obscuration still likely). Surface wind increasing to NW 15-30 kt gusting up to 25-40 kt Sunday. Snow levels falling to 5000-7000 ft MSL Sunday. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise SHORT TERM...KA LONG TERM....NF AVIATION.....NF ####018003761#### FXUS66 KSTO 162032 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 132 PM PDT Fri May 16 2025 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .Discussion... .Synopsis... Dry, warm, and breezy weather persists today, before a weather system arrives over the weekend. A slight chance of mountain/foothills thunderstorms north of Interstate 80 Saturday, is then followed by gusty and drying north winds Sunday and Monday. As a result, critical fire weather conditions are anticipated Sunday and Monday throughout the Valley and Delta due to the gusty winds and expected low relative humidity. Dry and hot weather then looks to follow, with areas of Moderate HeatRisk and elevated fire weather conditions through mid next week. && .Key Messages... * Fire Weather Watch in effect from 8 am PDT Sunday through 8 pm PDT Monday for Valley and Delta locations below 1000 feet. * Today: -Dry weather, warm temperatures, and periodically breezy winds persist with areas of Minor HeatRisk in the Valley. * Saturday: -Weather system begins to drop southward from Pacific NW. -10-25% probability of isolated thunderstorms across northeast foothills and Sierra/southern Cascades from Interstate 80 northward. -Temperatures cooling to near normal, with breezy winds throughout the day. * Sunday - Monday: -Current ensemble trends indicate the expected weather system following an inside slider trajectory through the region. -Gusty north to east winds expected to develop Sunday and Monday as this system progresses, with lingering breezy winds into Tuesday. -Probability of gusts 40 mph or higher: --Sunday: 30-50%, highest along and west of I-5 in the Sacramento Valley. --Monday: 20-40% across the central/southern Sacramento Valley and Delta. -Critical fire weather conditions expected Sunday and Monday, due to the combination of gusty northerly winds and low relative humidity in the Valley and Delta. * Tuesday - Thursday: -Warming trend expected early to mid next week, with areas of Moderate HeatRisk across the Valley. -North to east winds expected to remain diurnally breezy while very dry conditions prevail. -Elevated fire weather conditions anticipated. .Changes from previous forecast... -Moderate HeatRisk and elevated fire weather conditions looking to persist into the late week period. && .AVIATION... VFR conditions expected to prevail over Valley TAF sites next 24 hours. Surface winds will increase in response to a upper level trough moving into the Great Basin. For sites in the Northern Sacramento Valley; surface winds from the north around 15 knots, gusting 25-30 knots beginning around 12z Saturday. Onshore flow in the Central/Southern Sacramento Valley, Delta, Northern San Joaquin Valley's increase to around 20 knots, gusting to 30 knots around 10z Saturday. Over the western Sierra slope, surface winds gusting up to 40 knots beginning around 12z tomorrow. && .STO WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Sunday morning through Monday evening for Carquinez Strait and Delta-Central Sacramento Valley in Glenn, Colusa, Yuba, Northern Sutter, and Butte County Below 1000 Ft-Northern Sacramento Valley to Southern Tehama County Line Below 1000 Ft-Northern San Joaquin Valley in San Joaquin and Stanislaus Counties Below 1000 ft-Southern Sacramento Valley in Yolo-Sacramento Far Western Placer, southern Sutter and Solano County Below 1000 Ft. && $$